The present invention generally relates to a stator core for electric rotary machines such as electric motors, alternators, etc. and more particularly, to a coil inserting apparatus for inserting coils into slots of the stator core.
Conventionally, there have been employed a coil inserting apparatus of the fixed blade type as shown in FIG. 1, in which all blades (hereinbelow, referred to as "fixed blades") 3a are secured to a blade holder 2, as disclosed in U.S. Pat. No. 3,324,536, or the coil inserting apparatus of a movable blade type shown in FIG. 2, in which all blades (hereinbelow, referred to as "movable blades") 3b are secured to a coil pusher 5, as disclosed in U.S. Pat. No. 2,432,267, or the coil inserting apparatus of a movable blade type shown in FIG. 3, in which movable blades 3b and fixed blades 3a are provided and the movable blades 3b are secured to the coil pusher 5 with the fixed blades 3a being not secured to the coil pusher 5, as disclosed in U.S. Pat. No. 3,559,268.
However, the known coil inserting apparatus of the fixed blade type shown in FIG. 1 has drawbacks, such as that, since a large frictional resistance is produced between the fixed blades 3a and the coils, the coils are likely to be readily damaged during insertion thereof into slots of the stator core, and this known coil inserting apparatus can be used only with coils having wire diameters restricted within extremely narrow limits. It is to be noted here that the coils are prewound into the shape of closed loop and have two side portions and two end portions connecting the side portions. The prior art coil inserting apparatuses of the movable blade type shown in FIGS. 2 and 3 have an advantage that the resistance against the coil insertion is reduced, but are disadvantageous in that the coils are required to have the end portions of the coils increased in length in advance such that the coils are pushed upwardly in the axial direction of the blade holder 2. Thus, the known coil inserting apparatuses of the movable blade type have the disadvantage that, since an extremely large force is applied to the movable blades 3b and the coils, the coil inserting apparatuses of the movable blade type cannot be used stators having a winding in which the coil length is reduced to a length as short as possible and in which the opposite end portions of the coils are reduced in height so as to obtain compact electric motors, etc. accommodating the stators therein. Furthermore, since it is generally rather difficult to convert the coil inserting apparatuses of the fixed blade type to the coil inserting apparatuses of the movable blade type or vice versa, two kinds of coil inserting apparatuses, namely a coil inserting apparatus of the fixed blade type and a coil inserting apparatus of the movable blade type, are required to be provided, for example, in the case where two kinds of coils, one having a small insertion resistance force and the other having a large insertion resistance force, are required to be properly inserted into the slots of the same stator core.
Furthermore, in the known coil inserting apparatuses of the fixed blade type and the movable blade type, where the stator cores have different stack heights, bolts 1 in FIGS. 1 to 3 are loosened and then the blade holder 2 is pushed upwardly or downwardly such that the distance between upper ends of the fixed blades 3a and the movable blades 3b and upper ends of wedge guides 4 is set to a value of each of the stack heights plus a certain allowance and finally, then the bolts 1 and tightened, which requires tedious and time-consuming operations. Thus, the prior art coil inserting apparatuses of the fixed blade type and the movable blade type are inconven that a long time period is required for changeover to respective stack heights, in the production of stator cores having various stack heights.
In order to eliminate the above-described drawbacks of the conventional coil inserting apparatuses, the present inventors have previously proposed a coil inserting apparatus provided with a plurality of driving sources in U.S. patent application Ser. No. 321,928 filed November 16, 1981, now U.S. Pat. No. 4,433,475, as shown in FIG. 4. However, the coil inserting apparatus referred to above has such problems as that, since cylinders 10, 11 and 12 act as the driving sources and are not on a common axis, it is difficult to provide precise control of the speed of the coil pusher 13 and blades 14, and the overall length of the coil inserting apparatus is very large and the coil inserting apparatus is limited, in application, to stators having large sizes to some extent.